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Biologic Drug

A complex medication derived from living cells, including monoclonal antibodies, vaccines, and cell therapies, that treats serious conditions like cancer and autoimmune diseases.

How It Works

Biologics are large, complex molecules produced in living systems, bacterial, yeast, mammalian (typically CHO cells), or more recently human cell lines. They include monoclonal antibodies (Humira/adalimumab, Keytruda/pembrolizumab, Stelara/ustekinumab), recombinant proteins (insulin analogs, erythropoietin), fusion proteins (Enbrel/etanercept), vaccines, blood products, and advanced therapies like CAR-T cells (Yescarta, Kymriah) and gene therapies (Zolgensma, Casgevy). Unlike small-molecule drugs with defined chemical structures, biologics are characterized by primary sequence plus post-translational modifications (glycosylation, folding) that cannot be exactly replicated between manufacturers; this is why "generic" biologics are called biosimilars. Biologics are regulated under the Public Health Service Act section 351 via Biologics License Applications (BLAs), not NDAs. Manufacturing requires specialized facilities with bioreactors, extensive quality testing, and cold-chain logistics; a single biologic manufacturing facility typically costs $500M-1B to build. Biologics dominate the high-cost drug list: Humira peaked at $21 billion annual sales before biosimilar entry; Keytruda generated $27 billion in 2023; Ozempic/Wegovy combined exceeded $25 billion in 2024. They accounted for roughly 55% of total U.S. drug spending in 2023 despite being used by under 3% of patients. Biologics exclusivity under BPCIA (12 years from licensure, with 4-year filing bar) is the longest FDA exclusivity pathway, longer than any small-molecule protection. IRA negotiation eligibility for biologics begins 11 years post-approval, compared to 7 years for small molecules.

Related Terms

  • Biosimilar, A biologic product that is "highly similar" to an already approved reference biologic, with no clinically meaningful differences in safety, purity, or potency.
  • Specialty Drug, A high-cost medication, typically above $1,000 per month, that treats complex or chronic conditions and often requires special handling, storage, or administration.
  • Reference Product, The FDA-licensed biologic against which a biosimilar is compared and approved under BPCIA, equivalent to the brand-name innovator biologic.
  • Follow-On Biologic, An informal term for a biologic similar to an already approved innovator biologic, historically used before BPCIA created the formal biosimilar pathway in 2010.

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About This Definition

This definition is part of the DrugPrice Drug Pricing Glossary, 49 terms explaining how prescription drug pricing works in the United States. All definitions are written in plain language for patients, caregivers, journalists, and healthcare professionals.

this entity is one of the U.S. Medicare prescription-drug pricing concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the CMS Medicare Part D Drug Spending data data behind every per-entity page on the site.

In the CMS Medicare Part D Drug Spending data data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.

Source: CMS Medicare Part D Spending, 2026.